The present invention relates to a reactor power control apparatus, and more particularly to a reactor power control apparatus of a natural circulation reactor in which coolant is circulated by natural circulation. In addition, the present invention relates to a natural circulation reactor generation system of which includes the reactor power control apparatus. The present invention relates further to a method for controlling reactor power of a natural circulation reactor.
Generally, reactors are largely divided into a forced circulation type and a natural circulation type based on a circulation system of the coolant (cooling water) . The forced circulation reactor includes a recirculation pump such as a jet pump or an internal pump or the like. This pump supplies forcibly cooling water into the core.
Meanwhile, the natural circulation reactor does not include a recirculation pump as in the case of the forced circulation reactor. The cooling water is circulated by the natural circulation force which is based on the difference in density of the cooling water outside of a core shroud which surrounds a core and two-phase flow including steam and cooling water inside the reactor shroud.
In this manner, because the natural circulation reactor does not include a recirculation pump, when load variation of the reactor is demanded, it necessary to be changed the reactor power by operation of a control rod. However, in the case where control rod operation is used, there is a problem in that because the time constant is large from the operation of the control rod to when power of a generator or the like is changed, the following for the load variation becomes bad.
A natural circulation reactor in which thermal power of the reactor is changed without control rod operation is known (see Japanese Patent No. 2521256). Reactor power is changed by using a turbine steam (main steam) control valve and a turbine bypass valve in tandem to control thermal power from the reactor (see Japanese Patent No. 2521256).